PSYC 307 1st Edition Lecture 4Overview of Previous LectureI. Biological BackgroundsOverview of Current Lecture:II. Brain Developmenta. Neuronsb. Brain Maturationc. Experience-Expectant Plasticityd. Experience-Dependent Plasticitye. Studying Brain FunctionsIII. Prenatal Developmenta. Periods of Prenatal DevelopmentCurrent Lecture Sept. 11 – Brain Development I. Neurons: make up the braina. Made up of synapses that send signals between neurons and throughout the brain b. Gray matter: cell bodies and dendritesc. White matter: myelin sheaths, neural axons II. Brain Maturation: developmenta. Neurogenesis: birth of cells in neural tubei. Most nerve cells are born prenatally 1. Few are formed in adolescence or adulthoodb. Migration of cells: cells move to their correct location i. DNA tells them where in the brain to go ii. Glial cells transport them thereiii. Brain build in an inside out pattern – the newest cells are at the top of the brain, oldest in the middle 1. Hippocampus only part of the brain not built that way iv. Very organized layers/columns of cells c. Cell differentiation i. Develop important parts once they are in their correct location 1. Post natal d. Synaptogenesis: connection between neuronse. Myelination: occurs in adolescence f. Synaptic pruning: pathways become efficient by cutting down on the number of synaptic pathways i. Two years of age: an individual has the most synapses they will ever have 1. Centered in the visual cortex, low processing at this ageii. Different parts of the brain mature at different rates1. 3 years, peak of maturation in prefrontal cortex g. ** parts of brain diagramIII. Experience-Expectant Plasticity a. Brain development as a result of ubiquitous experiences i. Experiences common across all people/cultures1. Language, cognition, visual perception ii. Sensitive periods of development1. Specific “time periods” for developmenta. Ie: languageb. Ie: binocular vision – both eyes must work together to develop correctlyiii. Vulnerability of the brain IV. Experience-Dependent Plasticity a. Neural connections are created and reorganized as a function of experienceV. Studying Brain Functinsa. EEG, ERP, fMRI, etc.Sept. 11 – Prenatal DevelopmentI. Periods of prenatal developmenta. Germination (0-2 weeks)i. Zygote: sperm and egg come together (one cell)1. Takes 36 hours for first cell division (mitosis)a. 23 pairs2. Twinning occurs at this stage (monozygotic or dizygotic)ii. Blastocyst: takes 1 week1. Inner cells: embryonic disk new organism2. Outer cells: trophoblast, protective covering (turns in to placenta)iii. Implantation: end of the first week 1. Blastocyst implants in uterine liningb. Embryonic Period (3-8 weeks)i. Major development of organs and systems ii. 3 layers1. Endoderm: eventually forms digestive and respiratory systems2. Mesoderm: forms circulatory system, bones, muscle, internal organs3. Ectoderm: forms nervous system, sensory receptors, skin iii. Support systems develop1. Placenta2. Umbilical cord: connects fetus to placenta so that it can receive nutrients3. Amnion amniotic sac: forms buffer of protection, keeps skin moist iv. Major changes: 4-8 weeks 1. Rapid growth: ears, eyes, jaw, neck2. Limb buds form: arms, legs, fingers, toes 3. Fetus begins to respond to touch c. Fetal period (2-9 months)i. Most vital organs have already been formedii. Time of extreme growth/development for the fetus 1. 3rd month – lungs begin to expand and contract; sex can be determined by ultrasound (not always accurate)2. 2nd trimester (4-6 months)a. Mother can begin to feel the fetus moving i. Lanugo and vernix (protects the baby’s skin)b. Sucking; eyelashes, eyebrows, activityc. Eyes opening 3. 3rd trimester (7-9 months)a. Age of viability: if a baby is born during this time, it will need medical help and attention to live and grow i. Baby outside the womb that should still be insideii. Create womb-like environment so that they can continue to develop b. Cerebral cortex enlargesc. Fetus spends more time
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